I've been told that the condition of your finger nails tells a lot about your general health, and that lack of certain vitamins in your diet can lead to them being unhealthy.

Several weeks ago I had no moons on them at all. These are slowly coming back, but now I find I have deep ridges in them. The ridges feel a bit like corrigated iron.

Can any one please tell me what I'm lacking in my diet for my fingernails to have ridges like this?